The invention relates to compositions of rubbery polymer and extender oil. In one of its aspects the invention relates to the stabilization of such compositions against oxidative degradation. In another aspect of the invention stabilized compositions of rubbery polymer, extender oil, and asphalt are provided.
For several years rubberized asphaltic compositions have been used to produce membranes, mastics and sealants, which require special performance properties including water-resistance, flexibility, crack-resistance, adhesion and outdoor stability. The make-up of these compositions is generally 25-95 wt. percent asphalt and 5-25 wt. percent rubber with varying amounts of fillers, stabilizers, extender oils, etc. Because of the multiplicity of components, many users of such asphaltic products preblend some of the ingredients which are otherwise difficult or time consuming to incorporate. One such blend is an extender oil and the rubber which can be prepared by dissolving the rubber in hot extender oil. To this blend is added asphalt and other desired ingredients. It has long been suspected, although not confirmed, that rubbers of a certain type (e.g. conjugated diene/monovinyl aromatic copolymers) degrade when pre-dissolved in certain extender oils (e.g., paraffinic, naphthenic, aromatic) thereby altering properties of the resulting rubberized asphalt-based products. The use of stabilizers has generally been limited because of cost and the effective concentration required. The search for effective low cost stabilizers has continued. This invention embodies such a stabilization system. It is, therefore, an object of this invention to provide a method for stabilizing blends of oil and rubbery polymer against oxidative degradation. It is another object of this invention to provide stabilized compositions of rubbery copolymer, oil, and asphalt.
Other aspects, objects and the various advantages of this invention will become apparent upon reading this specification and the appended claims.